Large-scale Strain Research Articles

High spatial resolution φ-OFDR based on frequency-shift averaging and rotating vector summation

The coherent fading noise hinders the spatial resolution enhancements of phase optical frequency domain reflectometry (φ-OFDR). To mitigate the coherent fading noise, this study introduces frequency-shift averaging and rotating vector summation for strain measurements. The original Rayleigh backscattering signal was first divided into numerous sub-segments in frequency domain by using the frequency-shift averaging, and each sub-signal segment was transferred into vector signal with both intensity and phase information by using the rotating vector summation. Furthermore, a spatial position correction algorithm is incorporated to counteract the degradation of phase coherent, facilitating large-scale strain measurements. After optimizing the sub-frequency range and overlap ratio of the sub-signal in the frequency domain, we experimentally demonstrated that this method achieves strain measurement with a broad strain range of 2000 με, a high spatial resolution of 0.54 mm, and a high precision of 0.87%.

Large-Scale Atomic Strain Defects on Palladium Surfaces for Enhanced Oxygen Reduction and Zinc-Air Batteries.

Designing nano-electrocatalysts rich in surface defects is critical to improve their catalytic performance. However, prevailing synthesis techniques rely heavily on complex procedures that compromise defect extensiveness and uniformity, casting a high demand for methods capable of synthesizing large-scale crystalline defects. An innovative design strategy is herein proposed that induces ample strain/dislocation defects during the growth of palladium (Pd), which is well-known as a good oxygen reduction reaction (ORR) catalyst. The controlled defect engineering on Pd core is achieved by the tensile stress exerted from an intentionally applied Fe3O4 skin layer during synthesis, which changes the surface free energy of Pd to stabilize the defect presence. With such large-scale crystalline defects, this Pd catalyst exhibits significantly higher ORR activity than commercial Pt/C, enabling its promising future in zinc-air battery catalysis. Additionally, the protective Fe3O4 skin covering the catalyst also enhances its catalytic stability. Theoretical calculations show that the superior catalytic property of such defect-engineered Pd is associated with the correspondingly modified adsorption energy of *O intermediates onto its surface, which further improves the reaction rate and thus boosts ORR kinetics. Findings here are expected to provide a paradigm for designing efficient and stable metal catalysts with plentiful large-scale strain defects.

S. cerevisiae ERG5DeltaNTH1DeltaAMS1Delta Construction Enhancing Stress Tolerance for Ethanol Production Increase in the Presence of Inhibitors and Mechanism Analysis based on the Comparative Transcriptomics

Saccharomyces cerevisiae is considered the most promising large-scale production strain with ethanol as the main product. The fermentation of Saccharomyces cerevisiae is generally inhibited under various stress conditions. Various inhibitors in the hydrolysate severely inhibit yeast proliferation and yeast accumulation. In this study, S. cerevisiae ERG5, NTH1, and AMS1 were knocked out to improve the yeast stress tolerance by the Clustered Regularly Interspaced Short Palindromic Repeats Cas9 (CRISPR-Cas9) technology. The result indicated that the stress tolerance of S. cerevisiae ERG5ΔNTH1ΔAMS1Δ mutant (S. cerevisiae SCENA) was remarkably improved compared with the wild-type strain. The contents of fecosterol, trehalose, and mannan in S. cerevisiae SCENA were 1.67, 1.53, and 1.47 folds compared with those in the control. The ethanol concentration in S. cerevisiae SCENA reached 16.5 g/L, which was 1.23 folds compared with the control using rice bran hydrolysate. Further, the transcriptome analysis indicated down-regulated differential expression genes (DEGs) in S. cerevisiae SCENA were mainly from cellular response to glucose, cell periphery, and plasma membrane. Up-regulated DEGs were mainly from spore wall assembly, fungal-type cell wall assembly, and ascospore wall assembly. Thus, S. cerevisiae SCENA could effectively produce ethanol using the fermentation of lignocellulosic hydrolysate in the presence of inhibitors by regulating fecosterol, trehalose, and mannan metabolisms.

Theoretical and experimental study of strain localization phenomenon based on phase transition theory

In the study of large-scale localized strain features, localized strain can lead to energy release and seismic effects. From the macroscopic process of localized strain, it is found that localized deformation is accompanied by structural weakening, which is due to phase changes in rocks. The phase change corresponds to the secondary phase transition process in physics. The present study illustrates this phenomenon from the perspective of secondary phase transition theory in statistical physics, combining the localized strain features on a large scale. Theoretical analysis and experimental studies were carried out using three brittle rocks, including marble, granite and red sandstone. First, two perturbation methods, i.e., Krylov–Bogoliubov method and Poincare method, are used to calculate the higher-order control equations in analytical model. The influences of control equation coefficients on the strain localization process are analyzed. Then the uniaxial compression tests are carried out on the three rocks to record the strain process. Finally, the theoretical and experimental results are compared to analyze the strain localization phenomenon. The comparison results show that both the Krylov–Bogoliubov solution and the Poincare solution in the analytical model can well describe the evolution characteristics of localized strain. It indicates that the theoretical model is valid and has high accuracy. The Poincare method better simulates the nonlinear phenomenon of strain localization. The present study provides a new theoretical method to better understand the strain localization phenomenon.

A terahertz meta-sensor array for 2D strain mapping

Large-scale stretchable strain sensor arrays capable of mapping two-dimensional strain distributions have gained interest for applications as wearable devices and relating to the Internet of Things. However, existing strain sensor arrays are usually unable to achieve accurate directional recognition and experience a trade-off between high sensing resolution and large area detection. Here, based on classical Mie resonance, we report a flexible meta-sensor array that can detect the in-plane direction and magnitude of preloaded strains by referencing a dynamically transmitted terahertz (THz) signal. By building a one-to-one correspondence between the intrinsic electrical/magnetic dipole resonance frequency and the horizontal/perpendicular tension level, arbitrary strain information across the meta-sensor array is accurately detected and quantified using a THz scanning setup. Particularly, with a simple preparation process of micro template-assisted assembly, this meta-sensor array offers ultrahigh sensor density (~11.1 cm−2) and has been seamlessly extended to a record-breaking size (110 × 130 mm2), demonstrating its promise in real-life applications.

Inverse finite element method with energy-based regularization for deformation reconstruction and structural health monitoring

Distributed Fiber Optical Sensing (DFOS) can be used to perform compact, low-invasive and large-scale strain measurements, providing an important tool for strain-based deformation reconstruction and Structural Health Monitoring (SHM). However, most current deformation reconstruction methods are difficult to apply to the sparse uniaxial strain measurement conditions associated with DFOS, especially for structures with complex geometries. This work introduces an energy-based regularization method, i.e., a priori assumption that the actual deformation state is close to the state with the minimum deformation energy under the premise of satisfying the strain constraints, into inverse finite element method to perform load-independently deformation reconstruction under the condition of sparse uniaxial strain measurement. The Inverse Finite Element Method with Energy-based Regularization (iFEM-EBR) can naturally construct the DFOS-based deformation reconstruction model with quasi-forward finite element analysis without introducing additional mathematical processing. The sensitivity of this method to structural characteristics, such as material parameters, makes it a unique prospect in SHM.

Comparing local energy cascade rates in isotropic turbulence using structure-function and filtering formulations

Two common definitions of the spatially local rate of kinetic energy cascade at some scale $\ell$ in turbulent flows are (i) the cubic velocity difference term appearing in the ‘scale-integrated local Kolmogorov–Hill’ equation (structure-function approach), and (ii) the subfilter-scale energy flux term in the transport equation for subgrid-scale kinetic energy (filtering approach). We perform a comparative study of both quantities based on direct numerical simulation data of isotropic turbulence at Taylor-scale Reynolds number 1250. While in the past observations of negative subfilter-scale energy flux (backscatter) have led to debates regarding interpretation and relevance of such observations, we argue that the interpretation of the local structure-function-based cascade rate definition is unambiguous since it arises from a divergence term in scale space. Conditional averaging is used to explore the relationship between the local cascade rate and the local filtered viscous dissipation rate as well as filtered velocity gradient tensor properties such as its invariants. We find statistically robust evidence of inverse cascade when both the large-scale rotation rate is strong and the large-scale strain rate is weak. Even stronger net inverse cascading is observed in the ‘vortex compression’ $R>0$ , $Q>0$ quadrant, where $R$ and $Q$ are velocity gradient invariants. Qualitatively similar but quantitatively much weaker trends are observed for the conditionally averaged subfilter-scale energy flux. Flow visualizations show consistent trends, namely that spatially, the inverse cascade events appear to be located within large-scale vortices, specifically in subregions when $R$ is large.

The Mechanical Behavior and Constitutive Model Study of Coarse-Grained Soil under Cyclic Loading–Unloading in Large-Scale Plane Strain Conditions

To address loading and unloading issues in civil and hydraulic engineering projects that employ coarse-grained soil as fill material under plane strain conditions during construction and operation, cyclic loading–unloading large-scale plane strain tests were conducted on two types of coarse-grained soils. The effects of coarse-grained soil properties on shear behavior and various modulus relationships were analyzed. The research results showed that coarse-grained soils with better particle roundness exhibit significant shear dilation deformation; it was also found that low parent rock strength can lead to strain softening, and an increase in confining pressure suppresses shear dilation deformation. During the cyclic loading–unloading process, the initial unloading modulus (Eiu) > unloading–reloading modulus (Eur) > initial reloading modulus (Eir) > initial tangent modulus (Ei), with the unloading modulus considerably greater than the others. In finite element simulations and model calculations, it is essential to select appropriate modulus parameters based on the stress conditions of the soil to ensure calculation accuracy. In this work, an elastoplastic and nonlinear elastic theory was used to establish a cyclic loading–unloading constitutive model. By comparing the values obtained using this model with experimental measurements, it was found that the model can reasonably predict stress–strain variations during cyclic loading–unloading of coarse-grained soils under plane strain conditions.

Study on the dynamic embedment variation of shallow embedded submarine pipelines in sand

The clarification of the pipe–soil interaction mechanism is a critical link in the design of the in-situ stability of shallow embedded pipes in subsea areas, and the in-situ embedment of pipelines is an important parameter in the pipe-soil interaction mechanism. A large-scale plane strain model test was performed for a shallow embedded pipeline with horizontal cyclic motion in sand. Additionally, a numerical analysis model that is applicable to multicycle submarine pipe–soil interactions in sand was constructed, which can consider the dynamic change in the pore ratio of sand during the motion of a shallow buried pipeline. The development law of dynamic embedment and factors influencing the pipeline after multiple horizontal cycles were studied. A method for calculating the dynamic embedment of pipelines in sandy soil was proposed. The results reveal that horizontal cyclic movement of the pipe in sandy soil increases the embedment depth, and dynamic embedment rises by 1.09–11.78 times depending on the initial state of the pipeline. Furthermore, a soil berm rises on both sides of the pipe following cycling, and the sand around the pipe is sheared and shrunken, causing a large increase in soil resistance during the horizontal movement of the shallow embedded pipe.

Synergistic competition mechanism of phonon scattering in uniaxial (100) strain diamond: A first-principles study

The miniaturization of high-frequency electronic devices has led to heat accumulation in their components. The ultrahigh thermal conductivity of diamond makes it an ideal material for heat dissipation, but factors such as temperature changes during the working process, special structures, thermal stress, and lattice mismatch can affect performance. This study investigated the effects of stress, temperature, isotope purity, and feature size on the thermal conductivity of diamond using a first-principles method. The sensitivity to size effects of the thermal conductivity of uniaxially strained diamond differed according to the scale. Under a low temperature (100 K), and with a feature size of 1 µm, the thermal conductivity of diamond with large-scale tensile strain exceeded that of a diamond with small-scale strain, which was an anomalous phenomenon. Isotope purification did not significantly affect the variation rule of the thermal conductivity of strained diamond.

Nonlinear vibration analysis of graphene platelets reinforced nanocomposite doubly curved concrete panels subjected to thermal shock: Development of an artificial intelligence technique

When the temperature gradient across a component quickly changes, a phenomenon known as thermal shock occurs that exposes the component to fast variable thermal stresses and large-scale strains. One of the goals of this abrupt loading is to increase the capacity of different systems to withstand thermal shock. The nonlinear thermally induced vibration of doubly curved graphene nanoplatelet reinforced nanocomposite panels subjected to abrupt thermal shock is being studied right now. The bottom portion of the curved panel system is held at a reference temperature while the top portion is thermally shocked. The Crank-Nicholson technique and generalized differential quadrature (GDQ) are used to build up and solve the one-dimensional transient heat equation. The double-curved panel’s thermomechanical characteristics are temperature dependent; hence this equation is nonlinear. Based on the law of decoupled thermoelasticity, Kant’s theory, and von Karman’s assumption of some kind of geometric nonlinearity, the overall function of the doubly curved panel is established. After modeling the current system mathematically and comparing the current approach’s findings to those of earlier research, we revalidated the findings in a Python environment by comparing them to those of the Extreme Gradient Boosting (XGBoost) machine learning algorithm. This approach is founded on the “boosting” idea, which combines additive training techniques with the identification of weak learners to produce strong learners. The findings demonstrate that certain structural geometrical and physical factors are significant contributors to the double-curved GPLRC panel’s nonlinear frequency under thermal shock.

Large hydropower projects increase stressdespite compensation efforts: Evidence from the Brazilian Amazon.

Large hydropower projects continue to be built in developing nations, despite their known negative impacts. Large-scale energy projects strain local infrastructure and reduce access to infrastructure for households that live near them. Here we investigate the link between large-scale hydropower projects and stress. Our results suggest that these projects create stress through two mechanisms: strains on community resources and through the process of displacement. We also ask how compensation and resettlement programs condition these relationships. Using data from the Madeira river basin in the Brazilian Amazon, we find that hydropower projects increase stress by reducing access to energy, water, sanitation and land. Compensation provided was not sufficient to moderate this effect.

Flexible strain sensor based on PU film with three-dimensional porous network

Flexible strain sensors are widely used in wearable applications such as human motion and health detection, but it is challenging to prepare sensors with excellent performance, such as a wide sensing range and high sensitivity with a simple process and low cost. By taking the advantages of the electrostatic spinning technique that can prepare micro-structured films with fibrous porous networks, and this paper investigated the effect of the distance between the electrostatic spinning needle and the collection drum on the mechanical properties of the PU films produced. Then, the most mechanically excellent three-dimensional porous PU fiber film was selected as the substrate, and Carbon Black (CB) particles were selected as the conductive filler to prepare the CB/PU/Ecoflex strain sensor (CPESS) with a three-dimensional porous fiber network structure by spraying CB on the PU fiber film for the sensitive layer and applying a layer of biocompatible Ecoflex on the surface as the encapsulation layer. Owing to the substrates of this three-dimensional network microstructure with excellent mechanical properties such as high Young's modulus and elongation at break, the CPESS has an excellent sensing performance, with a detection range of 200 %, a sensitivity of up to 1443.95, rapid dynamic response of 50 ms, a low detection limit of (0.3 % strain), favorable repeatability, and excellent dynamic response at a large-scale tensile strain of 150 % − 200 %. The CPESS can be used to detect human joint movements and fine motion changes, and it exhibits great potential for smart wearable applications.

High-Performance transparent and flexible Zinc-Ion Solid-State batteries based on nanotube network and hydrogel electrolyte

Transparent and flexible electronics research is a lively and promising domain that holds immense potential for a plethora of innovative applications in consumer electronics, healthcare, and renewable energy sectors. It would be extremely beneficial to develop internal energy sources that are transparent and do not alter the visual appearance would. In this study, we introduce the design of a transparent and flexible zinc-ion solid-state battery (TFZSB), all of whose component elements, such as the electrode, electrolyte/diaphragm, and packaging, are made of transparent and soft materials. The electrodes have been constructed with a framework of nanotube (NT) networks, while the electrolyte is built from a polyacrylamide (PAM) hydrogel material. The suggested electrode design effectively leverages the outstanding optical properties and flexibility of the NT network, while the construction assimilates the PAM hydrogel for providing electrical protection and fabricate the electrolyte, culminating in a resilient interface, which confers exceptional electrochemical stability under varying mechanical strains. With a strong visible-light spectrum transmittance of >80 % and a retention Coulombic efficiency of >92 % under large-scale strains, the TFZSB demonstrates a mass specific capacity of 122.6mAh/g. This TFZSB constitutes a breakthrough in the realm of wearable and smart electronics, and holds the potential to unlock a multitude of opportunities in the future by bridging the domains of energy storage and flexibility/transparency.

Dual-Mode Stretchable Sensor Array with Integrated Capacitive and Mechanoluminescent Sensor Unit for Static and Dynamic Strain Mapping

Electronic skin (e-skin) has the potential to detect large-scale strain, which is typically achieved by integrating multiple strain sensors into an array. However, the latency and limited resolution of sensing have hindered its large-scale sensing applications. Here, we have developed a high-resolution detection sensing system capable of detecting static and dynamic strain with a simple fabrication process by combining capacitive and mechanoluminescent (ML) sensor units. An elastic polydimethylsiloxane (PDMS) composite film doped with ZnS:Cu and BaTiO3(BT) particles are fabricated as the functional film of the capacitive sensor. In contrast, the transparent electrode was fabricated on the surface of the as-prepared film. By incorporating BT nanoparticles into the elastic substrate, the ML intensity of the ZnS:Cu was improved up to 2.89 times that without BT addition, and the sensitivity of the capacitive sensor was increased as well. The capacitive part of the sensor presented a GF of 0.9 and good stability, while the ML part exhibited excellent performance, making it suitable for both static and dynamic sensing. Furthermore, the strain sensor integrated by 10 × 10 sensing units is demonstrated to detect large-scale strain with high resolution. Moreover, finger joint strain distribution tracking is achieved by attaching the strain sensor unit to the finger joint. With these characteristics, the e-skin may have great potential for bio-motion monitoring and human-computer interaction applications.

High-Resolution Optical Fiber Strain Sensor Array Based on Pound-Drever-Hall Technique With Fast Phase Regulation Method

Sensors that use Pound-Drever-Hall (PDH) technology benefit from the good performance and high resolution but are in shortage of large-scale multiplexing. This paper proposed a fast phase regulation method for the hybrid PDH multiplexing scheme based on space division multiplexing and time division multiplexing. Using both the information provided by an I/Q demodulator, the points from the error signal that the close-loop control requires can be rebuilt in the software with a phase rotation algorithm within a time period of less than 20 us. The relationship between the multiplexing scale and parameters selection is also given in this paper, showing that the system can have a larger multiplexing scale up to several tens sensors with appropriate parameters selection. A multi-channel strain array of up to 10 channels with a resolution better than 10 pϵ/√Hz@1 Hz over 50 Hz band per channel has been realized in this paper, and the system works with good channel crosstalk isolation. The experiment results show that the developed instrument has potential usage in the field of large-scale quasi-static strain measurement and earthquake observation.

Compressive strength of Aluminum-copper alloys at different temperatures

An Al-Cu alloy developed for applications requiring an alloy of moderate strength, weldability and good resistance to sea water, it is an excellent, versatile alloy ideal for many applications. The results obtained show that the level of spring back is strongly related to the imposed boundary conditions. If he is conceivable to overcome this problem by a “practical” tool for single curvature panels, it seems more delicate for double tooling curvature. In conclusion, if the prospects offered by this type of process seem attractive, a vast campaign of digital investigations must be considered in order to define more precisely the limiting radii of curvature that can be achieved without causing problems with spillage or buckling of the stiffeners, especially for double curvature applications. The boundary conditions considered should be able to be reproduced experimentally during shaping. For high strain rate testing, the only usable method to obtain information about the distribution of strains in the specimen is the use of high-speed photography. This method is used to visualize the location of deformations and fracture and also to measure the deformations of the specimen. The use of ultra-fast photography for large-scale tests strain rates can be performed in order to qualitatively study the behavior of materials. The proposed new geometry for the specimen will be modified by the use of high-speed photography.

Acorane sesquiterpenes from the deep-sea derived Penicillium bilaiae fungus with anti-neuroinflammatory effects.

Acorane-type sesquiterpenes comprise a unique class of natural products with a range of pharmaceutical effects. Genome sequencing and gene annotation, along with qRT-PCR detection, demonstrate that the deep-sea derived Penicillium bilaiae F-28 fungus shows potential to produce acorane sesquiterpenes. Chromatographic manipulation resulted in the isolation of 20 acorane sesquiterpenes from the large-scale fermented fungal strain. Their structures were established by the interpretation of spectroscopic data, together with X-ray diffraction, chemical conversion, and ECD data for configurational assignments. A total of 18 new sesquiterpenes, namely, bilaiaeacorenols A-R (1-18), were identified. Bilaiaeacorenols A and B represent structurally unique tricyclic acoranes. Compound 18 exhibited efficient reduction against NO production in LPS-induced BV-2 macrophages in a dose-dependent manner, and it abolished LPS-induced NF-κB in the nucleus of BV-2 microglial cells. In addition, marked reductions of iNOS and COX-2 in protein and mRNA levels were observed. This study extends the chemical diversity of acorane-type sesquiterpenoids and suggests that compound 18 is a promising lead for anti-neuroinflammation.

Phenotypic and Genomic Comparison of Staphylococcus aureus Highlight Virulence and Host Adaptation Favoring the Success of Epidemic Clones.

Methicillin-resistant Staphylococcus aureus (MRSA) of the sequence type 59 (ST59) and ST398 lineages has emerged in hospitals and displayed a higher virulent potential than its counterparts ST5 and ST239. However, the mechanism of the host cell-pathogen interaction and specific determinates that contribute to the success of epidemic clones remain incompletely understood. In the present study, 142 S. aureus strains (ST59, ST398, ST239, and ST5) were selected from our 7-year national surveillance of S. aureus bloodstream infections (n = 983). We revealed that ST59 and ST398 had a higher prevalence of the protease-associated genes hysAVSaβ, paiB, and cfim and enhanced proteolytic activity than the other lineages. ST59 and ST398 showed a higher expression of RNAIII and psmα and greater proficiency at causing cell lysis than other lineages. Furthermore, ST59 and ST398 were strongly recognized by human neutrophils and caused more cell apoptosis and neutrophil extracellular trap degradation than the other lineages. In addition, these strains differed substantially in their repertoire and composition of intact adhesion genes. Moreover, ST398 displayed higher adaptability to human epidermal keratinocytes and a unique genetic arrangement inside the oligopeptide ABC transport system, indicating functional variations. Overall, our study revealed some potential genomic traits associated with virulence and fitness that might account for the success of epidemic clones. IMPORTANCE Considerable efforts have been exerted to identify factors contributing to the success of epidemic Staphylococcus aureus clones, however, comparative phenotypic studies lack representation owing to the small number of strains. Large-scale strain collections focused on the description of genomic characteristics. Moreover, methicillin-resistant S. aureus infections constitute 30% to 40% of S. aureus bloodstream infections, and recent research has elucidated highly virulent methicillin-susceptible S. aureus strains. However, comprehensive research on the factors contributing to the success of epidemic S. aureus clones is lacking. In this study, 142 S. aureus strains were selected from our 7-year national surveillance of S. aureus bloodstream infections (n = 983) accompanied by a rigorous strain selection process. A combination of host cell-pathogen interactions and genomic analyses was applied to the represented strains. We revealed some potential genomic traits associated with virulence and fitness that might account for the success of epidemic clones.

Anomalous thermal response of bulk diamond to uniaxial (100) strain: A first-principles prediction

Diamond, a material that exhibits ultrahigh thermal conductivity with a sensitive thermal response to stress, is an ideal heat-sink material in the embedded cooling paradigm. This study uses first-principles calculations with the phonon Boltzmann transport equation to predict the variation rules of the thermal conductivity of diamond along the $\ensuremath{\langle}100\ensuremath{\rangle}$ crystal direction under strains at three orders of magnitude: 0.1%, 1%, and 10.5%. Density functional theory is used to predict the stress--strain dependence of diamond and the temperature-dependent thermal conductivity of unstrained diamond. The predictions are in good agreement with the experimental results. The calculated uniaxial strain--thermal conductivity dependence results reveal that the thermal conductivity of diamond abnormally increases by approximately 15% under small-scale uniaxial strain because of the weakened anharmonic interatomic force constants. Under large-scale strain, the thermal conductivity considerably decreases because of reduced phonon group velocities and increased numbers of phonon scattering channels. The findings in this study will guide analyses of the dependence of thermal conductivity on strain in other diamondlike structures, such as Group IV element-based materials. The abnormal thermal response at small strain is expected to lead to the realization of an artificial thermal conduction channel.